The movie takes a cue from Virginia Woolf's "Mrs. Dalloway," where the entire film occurs on one day, V-Day. From the beginning, the movie is a romantic masquerade with Kutcher at the center of the plot, waltzing in and out of storylines, as a florist who becomes more of a trusted confidant than salesman to his clients.

When Dempsey, who plays a heart surgeon, enters the flower shop with two orders (one for his wife and one for his girlfriend), Kutcher realizes that his best friend, a school teacher played by Garner, is Dempsey's unsuspecting mistress.

Quickly, other character identities are clarified. Hathaway plays a temporary receptionist, who's really a phone sex operator, who's actually a poet. Dane is a masculine football player on the verge of retirement, but he's really harboring a secret about his sexuality.

Roberts is a sexy army captain flying home for one night to see her sweetheart. But it turns out that she's not visiting her lover. MacLaine is a retired actress who's happily married to her soul mate, played by Hector Elizondo, until she confesses an indiscretion long ago. And the film's two self-professed V-Day haters, Biel, a publicist, and Foxx, a sportscaster, meet over work and by the end of the movie, mix business with pleasure.

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Somehow, most of the characters intersect toward the end at an Indian restaurant for an anti-Valentine's Day dinner party hosted by Biel. Garner breaks a giant heart piñata, Foxx dances to Bollywood music, and Biel encourages guests to burn relics of romances past. While it's not exactly the "Slumdog Millionaire" dance-off finale, the scene triggers a series of happy endings and plenty of concluding kiss-and-cry moments for the characters and the audience to savor.

Even with all the star wattage, though, the reviews have been tepid. Movie critic Marshall Fine calls the movie the "equivalent of an elaborately wrapped package which turns out to contain only styrofoam peanuts."

What may be more interesting, and probably just as convoluted as the movie's storyline, is the actual love lives of some of the cast members. See if you can follow their real-life romantic storylines below:

Bradley Cooper:

Cooper's star has been steadily rising in Hollywood with the success of "The Hangover," but the blue-eyed hottie has already been linked to several Hollywood A-list actresses.

Surprisingly, the 35-year-old actor was briefly married to actress Jennifer Esposito in 2006. The marriage broke up after four months. After that, Cooper was seen with Cameron Diaz, Elizabeth Banks, his "Nip/Tuck co-star Rhona Mitra, Molly Sims and Lake Bell.

Linked briefly with Jennifer Aniston, Cooper claimed they were "just friends." Soon after, he was spotted having dinner with Renee Zellweger, his co-star on the soon-to-be-released "Case 39."

Although the couple is rarely photographed together, their relationship appears to be heating up. According to People magazine, Zellweger celebrated Christmas with Cooper's parents in Los Angeles. The tabloids are also reporting that the couple recently purchased a California mansion.

Taylor Swift and Taylor Lautner:

It could have been so perfect but the tale of the two Taylors has no Hollywood ending, at least not in real life.

In "Valentine's Day," Lautner plays Willy, a track star and the boyfriend of Felicia, played by Swift. On screen, Lautner gives Swift a big French kiss. Off screen, romance between the two flickered for three months before it fizzled in December.

Friends of Swift told US Weekly that after a series of wholesome dates, including one over frozen yogurt alongside Swift's mom, the sparks just weren't there. "It wasn't really developing into anything, and wasn't going to, so they decided they were better as friends," the source told US. "There was no chemistry."

It also appears that Swift, 20, was just not that into Lautner, 17, as he was into her. "He liked her more than she liked him," the US source said. "He went everywhere he could to see her, but she didn't travel much to see him."

Or maybe Swift was still guarding her heart after her 2008 breakup with Joe Jonas, which she has said took place in a 27-second phone call and inspired one of the songs on her hit album "Fearless." She told Ryan Seascrest that Jonas was the only guy to really break her heart.

Ashton Kutcher:

In "Valentine's Day," Kutcher plays a shy florist who wakes up early to propose to his girlfriend, played by Jessica Alba, who seems more interested in her cell phone than marriage.

In real life, Kutcher, 32, is happily married to an older woman, 47-year-old Demi Moore. He wasn't always interested in older women, though.

Before Moore, Kutcher dated January Jones, who recently told GQ magazine that Kutcher was not supportive of her acting. "He was like, I don't think you're going to be good at this. So -- f*** you! He only has nice things to say now. If anything, I should thank him. Because the minute you tell me I can't do something, that's when I'm most motivated."

Moore also dated actresses Ashley Scott, Monet Mazur and Brittany Murphy. When Murphy died recently, Kutcher Tweeted, "2day the world lost a little piece of sunshine. .. see you on the other side kid."

After his breakup with Murphy in early 2003, Kutcher began seeing Moore. Although initially considered a fluke, their relationship has stood the test of time. They were married Sept. 24, 2005, in front of 100 close friends and family, including Moore's ex, Bruce Willis.

Jessica Alba:

As a young starlet who was ranked No. 1 on Maxim's Hot 100 list, Alba, now 28, was linked to several men, including actors Wilmer Valderrama, Mark Wahlberg, Scott Caan and athlete Derek Jeter.

But she came from a surprisingly conservative Christian background. At age 20, when she became engaged with her "Dark Angel" co-star Michael Weatherly, 12 years her senior, her parents were not happy. After the couple ended their relationship in 2003, Alba later spoke out about it: "I don't know [why I got engaged]. I was a virgin. He was 12 years older than me. I thought he knew better."

Alba again surprised the world in 2007 when she announced she was pregnant and engaged to the baby's father, producer Cash Warren. Now, with 19-month-old daughter Honor Marie, just finding time alone with her husband is a challenge.

Her real-life Valentine's Day, she told a reporter: "it's just a nice excuse to go on a date with my husband."

Julia Roberts:

The "Pretty Woman" star may be a happily married mom of three now, to husband-cinematographer Danny Moder, but it wasn't always so.

Before Moder, Roberts bounced from boyfriend to boyfriend, breaking an engagement and ending a marriage along the way. At 19, Roberts moved in with then 35-year-old Liam Neeson, whom she dumped for her "Steel Magnolias" co-star Dylan McDermott.

After "Flatliners," she and co-star Kiefer Sutherland got engaged but Roberts reportedly called off the wedding days before the ceremony, then ended up in the arms of Jason Patric. Then, she surprised the world with her secret elopement to singer Lyle Lovett, but the marriage ended less than two years later.

After Lovett, Roberts dated actor Benjamin Bratt for three years, telling McCalls he was
"all a girl could ever ask for." But Bratt reportedly split with Roberts because of her infidelity.

Photographed strolling in Paris with husband Moder after the Golden Globe awards, Roberts, at 42, finally looks happy in love. Presumably, she's pretty happy in her career as well -- according to New York Magazine's Vulture blog, she got paid $500,000 per minute to appear in "Valentines Day."

Jessica Biel:

The 27-year-old actress, whose three-year romance with Justin Timberlake is often said to be on the rocks, reportedly has no plans to celebrate Valentine's Day with the singer because she is too busy with work.

She told a reporter, though: "I love Valentine's Day. It's great to take a day out and celebrate loving and caring for people ... It's great."

But what people really want to know is whether the couple is still together. Last fall, break-up rumors exploded last fall with even Timberlake's grandmother fanning the flames with her comment to a British magazine: "Jessica was keen to marry but Justin isn't ready."

E! gossip columnist Ted Casablanca said the couple lacks spark.

"It's not working," Casablanca told ABCNews.com. "It's almost like they cancel each other out; same age, same look. There's no heat."

Biel, who dated Derek Jeter and Ryan Reynolds before Timberlake, called the split rumors "weird and sort of bizarre to deal with" in an interview with the UK's Independent in November.

Meanwhile, she has admitted to having a girl crush on two of her "Valentine's Day" co-stars, Roberts and Jennifer Garner.

"It's like, you're beautiful, you're cool, you look and seem like somebody I would want to hang out with and your career is awesome," Biel told a reporter about Garner.

Jennifer Garner:

At 37, Garner has been bouncing around Hollywood for some time but has still managed to avoid many of the pitfalls of romance.

After ending her three-year marriage to Scott Foley, whom she met on the set of "Felicity," Garner dated her "Alias" co-star Michael Vartan for about a year, before linking up with Ben Affleck.

Affleck proposed to Garner on her 33rd birthday while she was pregnant with their child. Married nearly five years and with two young daughters, Garner said her definition of romance has changed.

"Romance is romance, but in addition, romance can just be breakfast over the tops of heads and just getting through the day. You've got to find a way make that romantic," she said during the press junket for "Valentine's Day."

"Somewhere around the second kid, I thought, 'This is really turning into something.'" she joked.

Garner also defended her thin frame when actress Shirley MacLaine put her and the film's other young actresses on the hot seat asking them during the junket what they eat.

The senior of the group, MacLaine, 75, has spoken and written about her past loves -- and past lives.

In this lifetime, she has admitted to many affairs, including with actors Robert Mitchum and Danny Kaye, French singer and actor Yves Montand and former Australian foreign minister Andrew Peacock.

But she was also married for 28 years to producer-turned-businessman Steve Parker and they had a daughter Sachi.

In a 2007 interview with Britain's Guardian newspaper, MacLaine called herself a "serial monogamist," and said she broke up with her husband because "he was involved with another woman and I was all over the place with different men."

These days, she told the paper, her relationships are with nature and her spirituality.

ABC News' Jessica Reinis contributed to this report.

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